Battery unit comprising a plurality of battery cells and a device for protecting against thermal propagation

Abstract

A battery unit comprising a plurality of battery cells (9) arranged in a row, wherein each battery cell (9) comprises a plurality of battery elements and a battery cell casing surrounding the battery elements and having a degassing opening (23), and comprising a protective device extending along the row arrangement of the battery cells (9) and covering the degassing openings (23), wherein the protective device has at least one layer of foam material (21) and wherein the protective device is bonded to the battery cell casings by means of an adhesive bond.

Description

[0001] The invention relates to a battery unit with a plurality of battery cells.

[0002] A battery is an electrochemical storage device for electrical energy, in which stored chemical energy is converted into electrical energy through an electrochemical redox reaction during discharge. A battery can comprise one or, more commonly, several battery cells, which are arranged within a casing, usually in the form of a pouch or housing, to form a battery cell. Each battery cell may include two electrodes, a separator positioned between the electrodes for electrical separation, and an electrolyte acting as an ion conductor. The two electrodes of a battery cell may differ with respect to the active material they contain, making one electrode anodic and the other cathodic.Furthermore, a battery typically comprises two battery terminals integrated into the casing, which are electrically connected to the electrodes on the inside of the casing. All anodically active electrodes can be connected to one of the battery terminals, and all cathodically active electrodes to the other.

[0003] For particularly high performance requirements, such as those of a vehicle's traction battery, a large number of battery cells are combined in one or more battery units, whereby the battery cells can be connected electrically in series and / or parallel. Often, the battery cells within a battery unit are also mechanically connected to one another.

[0004] The battery cells of a motor vehicle, especially when they work together as a traction battery for an electrified powertrain with a relatively large overall battery capacity, can pose a significant hazard if they are damaged, for example, by improper use, internal short circuits, overcharging, overheating, aging, or as a result of a vehicle accident. Damage to a battery cell poses the risk of thermal runaway.Thermal runaway generally refers to the overheating of an exothermic chemical reaction or a technical device due to a self-reinforcing, heat-producing process. In a battery cell, this can result particularly from an internal short circuit caused by damage. In a battery unit, there is also the risk that thermal runaway in one battery cell will lead to thermal propagation, i.e., to the overheating of the other battery cells in the unit in a chain reaction.

[0005] US patent 2020 / 0212384A1 discloses a battery unit with safety features to reduce the risk of thermal propagation. The battery unit comprises a foam layer with multiple recesses. Furthermore, the battery unit may include a housing that contains the foam layer and multiple battery cells. The housing may also include a ventilation cavity that is in fluid-conducting communication with the multiple recesses of the foam layer.

[0006] CN 117 219 953 A describes a heat shield for use in a battery unit housing, the heat shield comprising three layers. A first layer is designed to be destroyed upon exposure to hot gas. A core layer can consist of a foam material. A third layer can be a steel plate.

[0007] The invention is based on the objective of reducing the risk of thermal propagation in a battery unit.

[0008] This problem is solved in a battery unit as claimed in claim 1 of the patent application. A protective device for such a battery unit and a battery system comprising such a battery unit are the subject matter of claims 13 and 14. Preferred embodiments of the battery unit, the protective device, and the battery system are the subject matter of further claims and are described in the following description of the invention.

[0009] A battery unit according to the invention comprises at least a plurality of battery cells, which may in particular be lithium-ion battery cells, arranged in a series. Each battery cell has a plurality of battery elements. The battery elements can each comprise two electrodes, a separator arranged between the electrodes for electrical separation of the electrodes, and an electrolyte serving as an ion conductor between the electrodes. This electrolyte can be liquid or solid and, particularly in the case of a solid electrolyte, can also function as a separator. The battery cells further comprise a battery cell casing that surrounds the battery elements. The battery cell casing can preferably be designed as a foil casing (so-called "pouch" casing) or as a housing, in particular as a dimensionally stable housing.A housing or structural component is considered "dimensionally stable" if its three-dimensional shape does not collapse under its own weight without external load. Preferably, such a housing or structural component can be designed to be dimensionally stable in such a way that it does not collapse under load from external forces occurring during normal use and, particularly preferably, is also not deformed to a significant degree. The battery cell casings each have at least one degassing opening, which is preferably (in a normal state of the battery cells) closed by means of a pressure relief valve, preferably in the form of a rupture element (e.g., a rupture foil), which is designed to fail structurally at a defined overpressure (e.g., between 5 bar and 6 bar) within the battery cell casing.The battery cells can further comprise a first battery terminal and a second battery terminal, the battery terminals being provided for the electrical connection of the respective battery cells to an external circuit. For this purpose, the battery terminals can be integrated into the battery cell casing such that a first section of them is located outside the casing and thus accessible for connection to the external circuit, while a second section, located within the battery cell casing, serves for an electrical connection with the battery elements. A first electrode of each battery element can be electrically connected to the first battery terminal, and a second electrode of each battery element can be electrically connected to the second battery terminal.

[0010] The battery unit according to the invention further comprises a preferably planar protective device extending along the row arrangement of the battery cells and (completely) covering the (in particular all) degassing openings, wherein the protective device has at least one layer of foam material, preferably consisting exclusively of a preferably elastic foam, i.e., a material with a cellular structure, wherein the cells are hollow. Preferably, the foam may have a closed-cell or mixed-cell structure. A closed-cell structure essentially comprises only cavities that are spatially separated from one another. Accordingly, the cell walls between the individual cavities are completely closed. A mixed-cell structure, on the other hand, comprises both interconnected and spatially separated cavities.The foam layer can preferably be completely closed and extend over the entire longitudinal and transverse dimensions of the protective device. At a minimum, however, the foam layer should completely cover the degassing openings of the battery cells. In the event of thermal runaway in a battery cell, the foam layer should allow the battery cell to degas through the corresponding degassing opening by being locally and, in particular, relatively easily destroyed by a gas flow exiting the battery cell casing through the degassing opening. This should allow for the release of any overpressure that has built up in the battery cell casing and the venting of the gas causing this overpressure.The protective device, and in particular the foam layer within it, protects the adjacent battery cells from this gas, which can reach very high temperatures, and also from particles contained within it, thus minimizing the risk of thermal propagation within the battery unit. The locally defined destruction of the foam layer can optionally be further facilitated by the fact that the foam layer, at least in the sections covering the degassing openings, has at least one weak point (designed for a defined failure), such as a preferably slit-shaped, complete or partial material weakening.

[0011] According to the invention, the protective device is further provided for by means of an adhesive bond that creates a material bond with the battery cell casings. This not only enables simple and therefore cost-effective assembly of the battery unit, but also increases the protective effect of the device with regard to thermal propagation by preventing gas escaping from the degassing opening of one of the battery cells from penetrating the protective device. Otherwise, this gas would come into contact, at least to a reduced extent, with the other battery cells and, in particular, with their associated degassing openings, which may each be sealed with a bursting element that is only relatively resistant to thermal and mechanical stress.

[0012] To prevent or at least minimize such undermining of the protective device, it is preferably provided that the strength of the adhesive bond (peeling preferably > 2 N / cm, particularly preferably > 6 N / cm) is higher than the tensile strength of the foam material layer, so that it is ensured that the foam material layer fails or is destroyed in a targeted manner in the area of ​​the degassing opening of a thermally continuous battery cell before a relevant loosening of the adhesive occurs in the area surrounding this degassing opening.

[0013] To provide advantageous protection against thermal propagation, the foam material layer can preferably be flame-retardant and preferably self-extinguishing. In particular, it can have a flammability rating of class V-1, preferably class V-0 (according to DIN EN 60695-11-10 and -20).

[0014] Preferably, the foam material layer can exhibit a relatively high compressibility, at least in the vertical direction, of, for example, at least 50%, preferably at least 75%, or, for example, 80%. This allows the foam material layer to advantageously compensate for shape and positional tolerances in the battery unit and / or to provide a relatively good sealing effect.

[0015] It is also preferably provided that the protective device and in particular the foam material layer has an electrically insulating effect, thereby enabling electrical separation of the individual battery cell casings, which may be electrically charged.

[0016] Preferably, the foam layer may be (partially or completely) composed of at least one silicone (or poly(organo)siloxane) and / or a synthetic rubber (e.g., EPDM (ethylene propylene diene monomer rubber)) and / or a polyurethane (PUR) and / or a polyolefin (PO). Using at least one of these materials advantageously fulfills the requirements placed on the foam layer. At least one flame-retardant additive may preferably be a component of the foam layer.

[0017] It is further preferred that the bonding is achieved using a pressure-sensitive adhesive (high-viscosity liquid; preferably in the form of a transfer adhesive tape or a double-sided coated adhesive tape) and / or using a non-metallic process material that adhesively bonds substrates. Pressure-sensitive adhesives comprise a permanently adhesive material that forms an adhesion to various surfaces under slight pressure. Such a bond exhibits advantageous properties with regard to its intended use in a battery unit according to the invention. In particular, a pressure-sensitive adhesive (especially one based on acrylate and / or silicone and / or rubber) can be advantageously suited to ensure a bond between the foam material layer and the battery cell casings with the required strength.

[0018] According to one embodiment of a battery unit according to the invention, at least one adhesive for forming the bond can be arranged on both sides of a carrier layer, wherein the carrier layer (with the adhesive) is arranged between the foam material layer and the battery cell casings. The carrier layer can, for example, be designed as a film. A "film" is defined as a flexible and thus easily deformable body whose length and width (which define the large areas of the film) are many times greater than its height (i.e., film thickness), wherein the height preferably corresponds to a maximum of 1 / 100, 1 / 500, 1 / 1000, 1 / 10000, or 1 / 100000 of the length and / or width of the film. In particular, a film can be dimensioned with such a small thickness that it would visibly deform under its own weight without support.

[0019] The use of such a carrier layer allows for relatively simple assembly of the battery unit and, in particular, facilitates advantageous handling of the protective device. On the other hand, such a carrier layer can negatively affect the failure behavior of the protective device in the area of ​​the degassing vents, so it may be advantageous not to use such a carrier layer and thus have only an adhesive layer between the foam material layer and the battery cell casing. Alternatively, however, it can also be provided that the carrier layer has a (defined failing) weak point, such as a preferably slot-shaped, complete or partial material weakening, at least in the sections covering the degassing vents.An advantageously usable support layer can also be designed in a net-like form and thus with a large number of relatively large through-openings, preferably forming at least 50% of the total area of ​​the support layer.

[0020] According to a preferred embodiment of a battery unit according to the invention, the protective device may have an additional layer on the side of the foam material layer facing away from the battery cells. The additional layer may preferably be made of PET (polyethylene terephthalate) or at least comprise PET. Furthermore, the additional layer may preferably be designed as a film, in particular as an adhesive film (single-sided adhesive tape). The additional layer may, for example, provide structural reinforcement of the foam material layer. Alternatively or additionally, the additional layer may also provide a seal or prevent moisture from penetrating the foam material of the foam material layer.To avoid the additional layer negatively affecting the failure behavior of the protective device in the area of ​​the degassing openings, it can be provided that the additional layer has a (defined failing) weak point, such as a preferably slot-shaped, complete or partial material weakening, at least in the sections covering the degassing openings.

[0021] The protective device may further preferably have a reinforcing layer on the side of the foam material layer facing away from the battery cells, wherein the reinforcing layer has at least one through-opening in at least one section covering the degassing openings of the battery cells. The reinforcing layer may, in particular, serve to structurally reinforce the protective device or the battery unit as a whole. For this purpose, it may preferably be made of metal and / or be dimensionally stable.

[0022] If a battery unit according to the invention has both an additional layer and a reinforcing layer, it is preferably provided that the additional layer is arranged between the foam material layer and the reinforcing layer.

[0023] According to a preferred embodiment of a battery unit according to the invention with a reinforcing layer, it can be provided that a preferably closed circumferential edge region of the foam material layer is covered by an edge section of the reinforcing layer that defines the at least one through-opening, thereby providing advantageous support for the foam material layer in at least one area that lies outside of an overlap with the degassing openings. It is further preferably provided that an annular sealing and / or adhesive element, for example applied as an annular bead of a pasty sealing and / or adhesive, is arranged in this edge section on the side of the reinforcing layer facing the foam material layer.This sealing and / or adhesive element advantageously achieves a seal and prevents moisture from penetrating the protective device and reaching the battery cells through the at least one opening. Alternatively or additionally, the sealing and / or adhesive element can also improve the structural strength of the protective device and the battery unit as a whole. In such a battery unit configuration, the preferably provided additional layer can also ensure advantageous adhesive bonding of the sealing and / or adhesive element to the foam material layer. This is particularly relevant if the foam layer is (also) made of silicone, as silicone is otherwise difficult to bond due to its low surface energy.

[0024] The invention also relates, in isolation, to a protective device for a battery unit with the features defining the protective device as described in the description and the claims.

[0025] The invention further relates to a battery system comprising one or more battery units according to the invention and a battery system housing in which the battery unit(s) is / are fixedly mounted. The reinforcing layer(s) of the battery unit(s) may preferably form a base of the battery system housing.

[0026] The invention further relates to a motor vehicle, in particular an electric motor vehicle with such a battery system. The battery system can in particular be a traction battery or at least a part of such a traction battery of the electric motor vehicle. An "electric motor vehicle" is defined as a motor vehicle that includes at least one electric traction motor by which the motor vehicle can be driven on its own. The motor vehicle can exclusively comprise the at least one electric traction motor as the drive motor ("electric vehicle") or the at least one electric traction motor can be provided in addition to another drive device, in particular an internal combustion engine ("hybrid vehicle"). The motor vehicle can in particular be a wheel-based and not rail-bound motor vehicle (preferably a passenger car or a truck).

[0027] The invention is explained in more detail below with reference to embodiments illustrated in the drawings. The drawings show, in simplified form: Fig. 1: a floor assembly of a motor vehicle; Fig. 2: a battery system of the motor vehicle according to the invention; Fig. 3: a battery cell of the battery system; Fig. 4: a longitudinal section through the battery cell; Fig. 5: a section of a cross-section through the battery system; Fig. 6: a section of a cross-section through the battery system; Fig. 7: a protective element for a battery system according to a first embodiment according to the invention; Fig. 8: a protective element for a battery system according to a second embodiment according to the invention; Fig. 9: a protective element for a battery system according to a third embodiment according to the invention; Fig. 10: a protective element for a battery system according to a fourth embodiment according to the invention; Fig. 11: a protective element for a battery system according to a fifth embodiment according to the invention; Fig. 12: a protective element for a battery system according to a sixth embodiment; Fig.13: a design form of the protective element according to the second design form (. Fig. 8 ) with slit-shaped weak points that completely penetrate a foam material layer of the protective element; Fig. 14: an embodiment of the protective element according to the second embodiment ( Fig. 8 ) with weak points that only partially penetrate the foam material layer (on a first side); Fig. 15: an embodiment of the protective element according to the second embodiment ( Fig. 8 ) with weak points that only partially penetrate the foam material layer (on a second side).

[0028] The Fig. 1Figure 1 shows a floor assembly 1, which is part of a body for an electric motor vehicle. The floor assembly 1 is known to provide, among other things, mounting points for components of a chassis and a drivetrain of the motor vehicle and can be made, at least partially, from formed sheet metal. The section of the floor assembly located between two axles of the motor vehicle is hereinafter referred to as the intermediate floor 2. This intermediate floor 2 is formed, among other things, by longitudinal beams 3, crossbeams 4, and floor panels 5, these components defining a receiving space (not visible) for accommodating a (traction) battery system 6 (see Figure 1). Fig. 2 and 5) of the motor vehicle. This receiving space and thus the battery system 6 are located below the floor panels 5 of the intermediate floor 2, with a flat body structure serving as underride protection also being arranged below the battery system 6 (not visible).

[0029] Battery system 6 is in the Fig. 2This is shown. It features a battery system housing that includes a mounting frame 7, which forms connecting openings 8 through which the mounting frame 7, and thus the battery system 6, is or can be connected to longitudinal members 3 and transverse members 4 of the intermediate floor 2. The battery system housing further comprises a housing base 19 and a housing cover (not shown). A plurality of battery cells 9 are arranged within the battery system housing and are electrically interconnected to provide, as a traction battery, a sufficient amount of electrical power to drive the vehicle's electric traction motor (not shown).

[0030] The battery cells 9 are designed as so-called prismatic battery cells 9 and therefore have a cuboid-shaped battery cell housing 10, which can be made of a metal (e.g., aluminum). The battery cell housing 10 can be provided on the outside with a functional layer, in particular an insulating layer (which has electrical insulating properties).

[0031] Battery elements are housed in the battery cell casing 10 (see below). Fig. 4Specifically, the battery elements are stacked in the form of an electrode-separator assembly (ESA) 11. Alternatively, a wound arrangement of the battery elements can also be provided. The ESA 11 comprises, in an alternating arrangement, a plurality of first electrodes 12a, which function as anodes during discharge of the battery cell 9, and a plurality of second electrodes 12b, which function as cathodes during discharge of the battery cell 9. As a result of the alternating arrangement of the electrodes 12, with the exception of the two electrodes 12 located on the outside of the stack or the ESA 11, a first electrode 12a is always arranged between two second electrodes 12b and a second electrode 12b is always arranged between two first electrodes 12a. Adjacent electrodes 12 are spatially separated by a separator 13 and are thus also electrically isolated from one another.Each battery cell consists of a first electrode 12a and a second electrode 12b, as well as a separator 13 arranged between them and impregnated with an electrolyte. The electrolyte allows ions to conduct between adjacent electrodes 12 via the separator 13 located between them.

[0032] Each of the electrodes 12 comprises a planar, foil-shaped substrate 14, which, for example, can be made of copper for the first electrodes 12a, intended as anodes, and of aluminum for the second electrodes 12b, intended as cathodes. In a rectangular section of this substrate, the two large surfaces of each electrode 12, located in the stacking direction of the ESV 11, are coated with an active material 15 to enable the different electrodes 12a and 12b to function as anodes or cathodes during use of the battery cell 9. At least in the area of ​​these rectangular sections of the substrates 14, and thus of the electrodes 12, these substrates and the corresponding rectangular separators 13 are stacked, resulting in the cuboid shape of the ESV 11.

[0033] On one transverse side of the rectangular section of each electrode 12, a region of the substrate 14 is provided in which it is not coated with the respective active material 15. This region of the electrodes 12 serves as a current collector 16, via which the individual electrodes 12 are directly or indirectly electrically connected to a corresponding battery terminal 17 of the battery cell 9. The current collectors 16a of all first electrodes 12a are connected to a first (17a) of the battery terminals 17, and the current collectors 16b of all second electrodes 12b are connected to a second (17b) of the battery terminals 17.

[0034] The battery cell housings 10 of the battery cells 9 each have a degassing opening 23 in a central section of one of their longitudinal sides, which is covered and thereby sealed by a foil-shaped bursting element 24 serving as a pressure relief valve. The bursting element 24 is designed and configured to prevent uncontrolled bursting of the battery cell housing 10 in the event of thermal runaway of the battery cells by releasing any gas that forms inside the battery cell housing 10 as a result of the thermal runaway and leads to a relatively large pressure increase into the environment via the bursting element 24, which then ruptures in a controlled manner.

[0035] The battery cells 9 of the battery system 6 are divided into a total of three battery cell groups, each of which is arranged in a row within a support structure 18 of the battery system 6. An intermediate cell layer (not visible) is arranged between each pair of battery cells 9.

[0036] The battery cell groups with the associated support structure 18 and a protective device each form a battery unit according to the invention.

[0037] The protective device comprises a protective element 20, which includes at least one layer of foam material 21, an annular sealing and adhesive element 24 and an associated section of the housing base 19 of the battery system housing (as a reinforcing layer of the respective battery unit).

[0038] The cuboid, planar (i.e., with a relatively small height compared to its longitudinal and lateral dimensions) protective element extends along the entire row arrangement of the battery cells 9, covering the degassing openings of all battery cells 9 in the battery unit. The degassing openings 23 of the battery cells 9 of the individual battery units, and thus also a central section of the respective protective element 2420, are located in the area of ​​an elongated through-opening 25 in the base 19 of the battery system housing when the battery system is assembled.This enables the gas escaping from this battery cell 9 to be discharged from the battery system housing via the associated through-opening 25 of the housing base 19 in the event of thermal runaway of one of the battery cells 9 and the resulting destruction of the associated bursting element 24 and the adjacent section of the protective element 20 (cf. . Fig. 5 This minimizes the risk that this escaping gas, which can have a very high temperature and also carry particles, could damage the adjacent battery cells 9 and thus lead to thermal propagation.

[0039] The flow of this gas from the area of ​​the degassing opening 23 of the thermally continuous battery cell 9 to the adjacent battery cells 9 is prevented as reliably as possible by the fact that the protective element 20 is bonded to the battery cell housings 10 and is also clamped or compressed within a closed circumferential edge section between the battery cell housings 10 and the base 19 of the battery system housing. The sealing and adhesive element 22 is also clamped or compressed within this edge section between the protective element 20 and the base 19 of the housing and effectively seals the gap formed between these components. This seal not only prevents gas escaping from a thermally continuous battery cell 9 from flowing to the adjacent battery cells 9, but also prevents moisture from the environment from penetrating the battery system housing (see Figure 1). Fig. 6 ), which is of particular importance because, as described, the underside of the battery system housing forms a section of the underside of the motor vehicle and may only be covered by the body structure serving as underride protection, although this cover may not be completely sealing.

[0040] The Figs. 7 to 13 show different design forms of the protective element 20.

[0041] The protective element 20 according to the Fig. 7The protective element 20 comprises a foam material layer 21 and a carrier layer 26, which is fully coated on both sides with a layer of adhesive 27 to bond the foam material layer 21 to the adjacent sections of the battery cell housings 10. Also shown is a film-shaped separating layer 28, which, in an initial state of the protective element 20 (i.e., before bonding to the battery cell housings 10), is arranged on the side of the carrier layer 26 facing away from the foam material layer 21 and serves as protection for the adhesive 27 located there. Before the protective element 20 is bonded to the battery cell housings 10, this separating layer 28 is removed to allow the adhesive to adhere to the battery cell housings 10.

[0042] The one in Fig. 8 The protective element 20 shown differs from the one according to the Fig. 7in that the foam material layer 21 is designed with a plurality of slot-shaped weak points 29, wherein these weak points 29 or slots completely or partially (with respect to the height extent; cf. Figs. 13 to 15 ) penetrate. The slot-shaped weak points 29 run transversely across the foam material layer 21 or the protective element 20 as a whole.

[0043] The one in Fig. 9 The protective element 20 shown differs from the one according to the Fig. 7The feature is that an additional layer 30 is provided on the side of the foam material layer 21 facing away from the carrier layer 26 and facing the base 19 of the battery system housing. This additional layer 30 ensures, in particular, a highly effective seal of the battery system against the ingress of moisture through the openings 25 in the base 19 of the battery system housing. This additional layer 30, which may, for example, be made of PET, can also advantageously interact with the sealing and adhesive element 22 to achieve, among other things, a beneficial adhesive effect between these components and thus between the protective element and the base 19 of the housing.

[0044] The protective element 20 according to the Fig. 10 also includes such an additional layer 30, whereby, deviating from the design according to the Fig. 9Both the carrier layer 26 and the additional layer 30 are designed with a large number of slot-shaped weak points 29 running in the transverse direction of the protective element 20.

[0045] The protective element 20 according to the Fig. 11 differs from the one according to the Fig. 8 by an additional layer 30 without weak points 29, as is also the case with the protective element 20 according to the Fig. 9 is planned.

[0046] The protective element 20 according to the Fig. 12 differs from the one according to the Fig. 9 by the fact that the additional layer 30 is designed with a large number of slot-shaped weak points 29 extending in the transverse direction of the protective element 20.

[0047] Instead of the carrier layer 26 (with or without weak points 29), in all embodiments only a layer of the adhesive 27 can be provided, which preferably covers the entire adjacent side of the foam material layer 21.

[0048] With the exception of any weak points 29 that may be present, the various layers of the protective elements 20 shown are preferably designed to be full-surface and thus free of openings.

[0049] The various layers of the protective elements 20 can, as shown, each have large rectangular areas, which can also have identical dimensions. Exemplary dimensions of the large areas could be: length: 1100 mm to 1200 mm; width: 100 mm to 150 mm. For the separating layer 28, however, it may be advantageous if it has an excess in its longitudinal and / or transverse extent compared to at least the carrier layer 26 (if present) and / or the foam material layer 21, in order to simplify removal before bonding to the battery cell housings 10. The slot-shaped weak points can, for example, have a slot length of 65 mm. The spacing between these weak points 31 can, for example, be 8 mm.

[0050] The foam material of the foam material layers 21 can preferably consist of silicone, synthetic rubber, PUR or PO. An advantageous layer thickness (extent in the vertical direction) of the foam material layer 21 can, for example, be 3.5 mm to 4 mm. Reference symbol list

[0051] 1 Base assembly 2 Intermediate floor 3 Longitudinal beam 4 Cross beam 5 Base plate 6 Battery system 7 Housing frame 8 Connection opening 9 Battery cell 10 Battery cell housing 11 Electrode-separator assembly (ESV) 12 Electrode 12 First electrode 12 Second electrode 13 Separator 14 Substrate 15 Active material 16 Current collector 16 First current collector 16 Second current collector 17 Battery terminal 17 First battery terminal 17 Second battery terminal 18 Support structure 19 Housing base 20 Protective element 21 Foam layer 22 Sealing and adhesive element 23 Degassing opening 24 Burst element 25 Through-hole in housing base 26 Carrier layer 27 Adhesive 28 Separation layer 29 Weak point 30 Additional layer

Claims

1. Battery unit comprising a plurality of battery cells (9) arranged in a row, wherein the battery cells (9) each comprise a plurality of battery elements and a battery cell casing surrounding the battery elements and having a degassing opening (23), and comprising a protective device extending along the row arrangement of the battery cells (9) and covering the degassing openings (23), wherein the protective device comprises at least one layer of foam material (21), characterized by the fact that the protective device is bonded to the battery cell casings (10) by means of an adhesive bond.

2. Battery unit according to claim 1, characterized by the fact that the strength of the bond is higher than the tensile strength of the foam material layer (21).

3. Battery unit according to claim 1 or 2, characterized by the fact thatthe foam material layer (21) has a flammability of class V-1 or V-0 according to DIN EN 60695-11-10 and -20 and / or is electrically insulating.

4. Battery unit according to one of the preceding claims, characterized by the fact that the foam material layer (21) is partially or completely composed of a silicone and / or a synthetic rubber and / or a polyurethane and / or a polyolefin and / or comprises a flame-retardant additive.

5. Battery unit according to one of the preceding claims, characterized by the fact that the bond is formed by means of an adhesive material (27).

6. Battery unit according to one of the preceding claims, characterized by the fact that at least one adhesive (27) is arranged on both sides of a carrier layer (26) to form the bond, or only one adhesive (27) is arranged between the battery cell casings and the foam material layer (21).

7. Battery unit according to one of the preceding claims, characterized by the fact that the protective device has an additional layer (30) on the side of the foam material layer (21) facing away from the battery cells (9).

8. Battery unit according to claim 7, characterized by the fact that the additional layer (30) is made of PET.

9. Battery unit according to one of the preceding claims, characterized by the fact that the protective device on the side of the foam material layer (21) facing away from the battery cells (9) has a reinforcing layer, wherein the reinforcing layer has at least one through-opening (25) at least overlapping the degassing openings (23) of the battery cells (9).

10. Battery unit according to claim 9, characterized by the fact that an edge area of ​​the foam material layer (21) is covered by an edge section of the reinforcement layer which limits the at least one through-opening (25).

11. Battery unit according to claim 10, characterized by the fact that a sealing and / or adhesive element (22) is arranged in the edge section on the side of the reinforcement layer facing the foam material layer (21).

12. Battery unit according to one of the preceding claims, characterized by the fact that the foam material layer (21) and / or the additional layer (30) and / or the carrier layer (26) has at least one defined weak point (29) which is located in a section covering at least one of the degassing openings (23).

13. Protective device for a battery unit according to one of the preceding claims, comprising the features defining the protective device as stated therein.

14. Battery system comprising one or more battery units according to any one of claims 1 to 13 and a battery system housing in which the battery unit(s) is / are fixedly mounted.

15. Battery system according to claim 9 or one of the claims dependent on claim 9 and according to claim 14, characterized by the fact that The reinforcement layer(s) of the battery unit(s) form a housing base (19) of the battery system housing.

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